Understanding Tire Pressure: The Dangers of Under- and Overinflating

February 16, 2017

How do I check my tire pressure?

Knowing how to check your tire pressure is an important part of vehicle ownership. Maintaining your tires' air pressure will provide you with a smoother ride and even help lower your vehicle's gas usage. Here's how to check your tire pressure and add air if you find that it is needed.

Grab a tire gauge

First up, you will need access to an air pressure gauge. You can find these at most gas stations, where they are generally attached to the air compressor (which you will use to add air to the tire if need be). Alternatively, You can also purchase a gauge of your own from any auto parts store and trust us, it's a worthwhile investment. Not only can you use it to check your tires' air pressure regularly, but your own gauge is also likely to be more accurate than the gas station's gauge.

Gauges come in several different variants: stick, digital, and dial. Stick-like gauges resemble a writing utensil and are inexpensive and small, although they can at times be difficult to read. Digital gauges employ an electronic display, some even illuminated, which are decidedly easy to read. On the other hand, digital gauges are more susceptible to damage from impact, dirt, or dust and utilize batteries which must be replaced every so often. Dial tire gauges use an analog pressure readout illustrated by a needle. Several of the gauges boast added features such as shock-resistant displays and bleeder valves, but are not necessarily more accurate. Moreover, these gauges are often bulkier and more expensive than their counterparts.

Determine the right pressure for your tires

Next, you will need to find the manufacturer's specifications for tire pressure, as they vary from vehicle to vehicle. Look for a sticker on the driver's side door indicating the PSI (pounds per square inch). If you don't see it there, it could also be in the glove compartment. If you do not find the information at either of those locations, check your owner's manual. You may also find a pressure reading on the tire. Be wary because this is the maximum load of the tire, rather than the recommended pressure.

Add air to your tires

Then, head to the gas station. Be sure to take plenty of quarters with you, as it will cost a few dollars. When you park, allow your tires to cool off for a few minutes. If you take the reading while they are still warm, the results may be inaccurate.

Remove the cap from the air valve of your tire, and put it in your pocket so you don't lose it. Push the gauge firmly over the valve until you see a reading.

If the reading shows that your tire needs air, give it the once-over; filling a tire that has a puncture is dangerous. If you don't see any problems, push the nozzle of the air compressor over the valve and add air using short bursts. Unless the compressor allows you to pre-set how much air to add, check the pressure again (with the gauge) after each burst.

Be sure to stop the compressor when you no longer hear air being released into the tire so you don't over-inflate the tires. When you have finished, replace the valve cap by turning it until it fits snugly over the valve. As a rule of thumb, check your tires' pressure once a month. Under-inflated tires can waste fuel economy, cause your tire to wear faster, and even compromise handling and braking making your ride unnecessarily dangerous.

Potential dangers of overinflated tires

Over-inflated tires don’t grip the road as well as properly inflated tires, which results in less traction and poor handling. This problem will be magnified with wet conditions, so summer storms may compromise your ability to steer and lead to unsafe driving conditions.

Improper inflation will also increase your risk of a blowout, or when your tire rubber loses its bond with the rim. Blowouts aren't just the result of too much air pressure, but can also happen with too little. Make sure to check for the "Goldilocks Zone," ensuring your tire pressure is at its optimal PSI.

Summer's effect on tires

For every 10-degree increase in the temperature of the air outside, the pressure of your tires will change about one to two PSI. When recommended tire pressure is typically between 30 to 35 PSI (pounds per square inch), the summer heat can certainly knock you out of the acceptable range!

About the Author

John Stahel is an automotive expert at RepairPal, the leading online source of auto repair resources and estimates. With many ASE Master certified mechanics on staff who have decades of experience, RepairPal knows all the fine points of car repair.

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